Field of the Invention
The present invention relates to a resin composition for golf balls. The invention relates in particular to a resin composition which is well-suited for use as a golf ball cover material.
Prior Art
Not all golf balls lately are white; a variety of colored balls have appeared on the market in response to golfers' preferences. For example, colored golf balls of various types that confer stylishness and elegance have been proposed as golf balls for women.
Various types of colored golf balls, including orange, pink, blue and yellow balls, are provided by using a transparent or semi-transparent resin material as the base polymer of the cover outermost layer, and mixing together with this base resin various types of pigments, dyes and aggregates.
However, particularly when trying to provide colored golf balls having a deep fluorescent color, in order to improve releasability from the mold during molding of the cover material, it is sometimes necessary to make adjustments that increase the content of fatty acid or fatty acid metal salt in the cover material and moreover increase the content of colorants, which worsens paint film adhesion.
Also, when the golf balls are marked by stamping the cover surface with lettering and images such as a logo or name, the frequency of stamping transfer defects increases.
In the field of golf balls, technical art relating to surface treatment for promoting adhesion between layers is disclosed in, for example, JP-A H10-179795, H11-137726, 2003-339912, 2009-131631, 2013-132312 and 2014-90957. However, even with such art, improvements in paint film adhesion remain inadequate.
It is therefore an object of this invention to provide a resin composition for golf balls which improves adhesion between the cover material and paint, minimizing the occurrence of uneven painting.